Co-Overexpression of Ankyrin Repeat Domain-Containing Protein 2A and Vacuolar H⁺-Pyrophosphatase Enhances Salt Tolerance through Auxin Homeostasis in Cotton.

Salinity is a major abiotic stress that severely affects crop productivity. Our previous study demonstrated that overexpression of Arabidopsis vacuolar H+-PPase (AVP1) enhances salt resistance by promoting lateral root development and biosynthesis of long-chain unsaturated fatty acids. In the present study, it was demonstrated that co-overexpression of the ankyrin repeat domain-containing 2A (AKR2A) and AVP1 contributes to the low sodium accumulation in the cytoplasm by facilitating Na⁺ efflux from the cell membrane and Na⁺ influx in the vacuole under salt stress, as validated by noninvasive microtest technology and confocal laser scanning microscopy. Furthermore, it revealed that AVP1 is the substrate of AKR2A protein. AKR2A helps AVP1 in the improvement of salt tolerance in plants. Additionally, AKR2A assists AVP1 in facilitating auxin polar transport, thereby contributing to lateral root development. The study elucidates the salt-resistant mechanism underlying the interaction between AKR2A and AVP1, which will be helpful for salt-tolerant cultivation in plants.